Questions Flashcards
In a transformer, sections of both primary and secondary windings are usually wound on each limb to.
Reduce magnetic leakage
Silicon steel is used for the laminations in a transformer core because it?
Has high permeability
In a transformer the component of no load current which lags the primary voltage by 90* is the
Magnetising Current
The secondary voltage of a transformer is produced by
Mutual Induction
The primary and secondary currents of a single phase transformer are approximately
180 degrees out of phase
With increasing non-inductive load the secondary terminal voltage of a single phase transformer would
Fall Slightly
The secondary power factor of a three phase transformer is dependant on
Power factor of the load
The hysteresis loss in a transformer
Is proportional to the frequency
If the load on a transformer is doubled, the iron losses are
Constant
The efficiency of a transformer
Varies with the load
If the acidity of transformer oil has reached an unsatisfactory level the oil should be
Run through filters for reconditioning
A positive crackle test of transformer oil would reveal the presence of
Water
In order to obtain maximum cooling effect a transformer tank should be
Tubed
High grade silicon steel is used for transformer cores because it
Reduces hysteresis loss
The no-load current of a transformer is
The phasor sum of the magnetising and iron loss currents
